Caption: Cosmic rays research. A video display of the MACRO (Monopole Astrophysics and Cosmic Ray Observatory) experiment simulating the detection of a group of highly energetic muons. Blue areas indicate detection of the muons in MACRO. MACRO's detectors form a structure 70 metres long and 15m high. MACRO is situated under 1400m of rock in the Gran Sasso Laboratory, Italy, the largest underground laboratory in the world. The muons detected by MACRO are created by the interaction between cosmic rays and the atoms in the upper atmosphere. MACRO is also looking for magnetic monopoles, exotic particles which have not been seen so far.